This invention relates generally to cascode amplifiers and more particularly to amplifiers of such type which are adapted to amplify cable television signals.
As is known in the art, in transmitting television signals through cables, amplifiers are needed at various points along the transmission path. One type of amplifier used for this purpose is shown in FIG. 1. Such amplifier includes two pairs 12, 14 of silicon transistors. Each pair of transistors is connected in a cascode configuration. The two pairs of transistors are driven by an input transformer 16 and the outputs of the pairs are connected to an output transformer 19. The two pairs of transistors 12, 14 are biased to operate in a linear, class A push-pull configuration. Amplifiers of this type are available and operate from 50 MHz to 550 MHZ.
In the future it is expected that the upper limit of the band will increase to 1000 MHz in systems which would carry at least 110 asynchronous analog signals. Intermodulation distortion must be minimized in such a system. It is expected that the peak power required per output transistor will 1.9 watts at 1 db compression point and that the gain required will be 18-20 db. Further, the amplifier must be economically practical.